JPH02304814A - Round type electric cable for oil well - Google Patents

Abstract

PURPOSE:To prevent infiltration of high temperature oil or gas with power line cores and a jacket stuck to each other and a gap minimized by coating each power line core with an insulating body formed through extrusion press in two layers respectively made of two different kinds of elastomer rubber, applying a reinforcing layer thereon, standing thus obtained three power line cores and extruding elastomer rubber thereon to cover them. CONSTITUTION:A conductor 1 is coated by concurrently extruding an hard inner layer 2a of an insulating body and an outer layer 2b of a thin hide of soft and easily adhesive ethylene propylene rubber. Then each power line core is formed by applying a reinforcing layer 3 on the conductor 1 with a roughly wound braid having heat resistance and oil resistance. The reason of such processes is to force the insulator outer layer 2b to make physical contact with a sheath inner layer 4a. Moreover the sheath inner layer 4a and a sheath outer layer 4b of the thin hide are concurrently extruded on three stranded power line cores to coat them, and moreover a spiral tube armour 5 is applied on the outer periphery. This enables infiltration of oil or gas between the insulated body and a sheath to be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric cable, particularly a round electric cable for oil wells.

[Prior Art] Oil well electrical cables are widely used to supply power from the ground to oil extraction pumps that pump crude oil from oil wells. This oil well electric cable will be explained below with reference to the cross-sectional view of FIG. 2. Three power wire cores each having a reinforcing layer 3 applied to an insulator 2 in which a conductor 1 is coated with elastomer rubber are twisted together, a sheath 4 made of elastomer rubber is fully extruded, and a helical tube sheath 5 is further applied around the outer periphery of the wire core. It is common to have one.

[Problems to be Solved by the Invention] Electrical cables for oil wells are used in harsh atmospheres due to their nature, so high temperature oil and gas easily enter the inside of the cables. It is desirable for the materials to be in close contact with each other to prevent hot gas from penetrating between them, but in conventional cables as mentioned above, the adhesion between the insulator and sheath is insufficient, so it is inevitable that High temperature and high pressure gas may enter. On the other hand, oil extraction pumps are periodically raised to the ground for maintenance purposes, but at that time, the pressure and temperature drop rapidly, causing the invading gas to expand, causing the crease to expand and break. It is easy to cause problems such as

This invention was made in view of these points, and it is an oil well round that can bond a power line core coated with an insulator and a jacket to minimize the gap between them to prevent the intrusion of high temperature oil and gas. The purpose is to provide type electrical cables.

[Means and effects for solving the problem] This invention has the following features:
In a round electrical cable for oil wells, an insulator is made by extruding two different types of elastomer rubber into two layers, a reinforcing layer is applied on top of this insulator, three of these power wire cores are twisted together, and two different types of elastomer rubber are extruded. It is characterized by being constructed by extrusion coating of elastomer rubber.

Therefore, the thin skin part of the outer layer of the insulator and the thin skin part of the inner layer of the sheath are made of ethylene propylene rubber, which has excellent adhesive strength, so that they are firmly bonded to each other, preventing gas from entering, and especially improving pressure resistance. This is a significantly improved round electrical cable for oil wells.

Embodiments] The present invention will be described in detail below based on the drawings. 1st
The figure shows a cross-sectional view of a round electrical cable for oil wells, with conductor 1
A hard inner layer 2a of an insulator and a thin outer layer 2b of soft and easily adhesive ethylene propylene rubber are simultaneously extruded and coated. Then, a reinforcing layer 3 made of a heat-resistant and oil-resistant loosely wound braid is applied thereon to form a power line core.

This is to bring the insulator outer layer 2b and the sheath inner layer 4a formed thereon into physical contact.

The three power wire cores thus formed are twisted together, a thin sheath inner layer 4a and a sheath outer layer 4b are simultaneously extruded and coated, and a helical tube sheath 5 is further applied around the outer periphery.

Both the insulating inner layer 2a and the sheath outer layer 4b are made of a material that has excellent oil resistance and heat resistance, and is hard and mechanically strong. This material may be formed from a composition containing, for example, 100 parts by weight of ethylene propylene rubber having an iodine value of 20 or less, 2 to 10 parts by weight of a cyanurate crosslinking aid, and 50 to 150 parts by weight of vinylsilane-treated calcined clay.

In addition, a thin outer layer 2b of an insulator and a thin inner sheath layer 4a
is formed by a formulation with excellent adhesive strength. As for this material, for example, 100 parts by weight of ethylene propylene rubber with an iodine value of 20 or less and 2 to 10 parts of cyanurate crosslinking agent are used.
Parts by weight, 50 to 150 parts by weight of calcined clay and 1 part by weight of silicic anhydride
It is preferable to form the composition with a composition containing ~10 parts by weight.

Therefore, the hard insulator inner layer 2a and the hard outer sheath layer 4b
A thin insulator outer layer 2b and a thin sheath inner layer 4 sandwiched between
By co-extruding a thin layer of ethylene propylene rubber, which is soft and easily adheres to a, it becomes possible to further enhance the adhesion effect. In addition, insulators 2 a, 2 b
By applying a coarsely wound braid of, for example, nylon 66 as the reinforcing layer 3, the insulators 2a, 2b and the sheaths 4a, 4b are directly and firmly contacted.

In the above embodiment, an example in which the number of wire cores is three was explained, but it is needless to say that the number of wire cores is not limited to this, and it is possible to use a plurality of wire cores.

[Effects of the Invention] As explained above, in the oil well round electric cable of the present invention, the outer layer of the insulator and the inner layer of the sheath are easily bonded together, so that gas can be prevented from entering between the insulator and the sheath. This makes it an excellent cable that can be used especially in oil wells with high pressure.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the configuration of an oil well hook cable for use in an oil well according to the present invention, and FIG. 2 is a cross sectional view showing the configuration of a conventional oil well hook cable for use in an oil well. 1... Conductor 2... Insulator 2a... Insulator inner layer 2b... Insulator outer layer 3... Reinforcement layer 4... Sheath 4a... Sheath inner layer 4b... Sheath outer layer 5.・・Spiral pipe chaining

Claims (3)

[Claims] (1) A round electric cable for oil wells that supplies power to oil extraction pumps that pump up crude oil has an insulator made of two extruded layers of two different types of elastomer rubber, a reinforcing layer on top of the insulator, and A round electrical cable for oil wells, consisting of multiple power wire cores twisted together, two different types of elastomer rubber source extruded into two layers, and a helical tube sheath installed on top. (2) The inner layer of the insulator and the outer layer of the sheath are made of hard elastomer rubber with excellent oil and heat resistance, and the thin skin of the outer layer of the insulator and the thin skin of the inner layer of the sheath each have excellent adhesive strength. The round electrical cable for oil wells according to claim 1, characterized in that the structure is formed from a composition comprising: (3) The inner layer of the insulator and the outer layer of the sheath have an iodine value of 20
It is formed from a composition containing 100 parts by weight of the following ethylene propylene rubber, 2 to 10 parts by weight of a cyanurate crosslinking aid, and 50 to 150 parts by weight of vinylsilane-treated calcined clay, and further includes the thin skin part of the outer layer of the insulator and the inner layer of the sheath. 2 to 10 parts by weight of a cyanurate crosslinking aid, 50 to 150 parts by weight of calcined clay, and 1 to 1 to 100 parts by weight of silicic anhydride to 100 parts by weight of ethylene propylene rubber whose thin skin part has an iodine value of 20 or less.
3. The round electrical cable for oil wells according to claim 1, which is formed of a composition containing 10 parts by weight or 1 to 10 parts by weight of hydrosilicic acid.